Wall ironing tool pack with redraw die

ABSTRACT

A wall ironing tool pack is disclosed, incorporating one or more wall ironing dies and a redraw die to reduce the cup shaped work piece to dimensions for wall ironing, wherein said reduction may amount to about 30 percent, and whereby the risk of fractures, or wrinkling of the work piece is avoided. One or more ironing dies and the redraw die are held in a holder and clamped by means of an annular hydraulic cylinder and piston disposed between any two rings. Hydraulic pressure supplied to said cylinder to actuate said piston is controlled by means of a regulator, whereby adjustment of the pressure on the cup to be redrawn may be made rapidly during operation, to insure the desired redrawn cup for subsequent wall ironing without risking fractures if the pressure is too high, or wrinkles if the pressure is too low, and maintaining the several dies in clamped relation.

United States Patent [191 Hasselbeck July 30, 1974 Appl. No.: 368,722

[75] Inventor:

[1.8. Ci. 72/349, 72/351 Int. Cl B21d 22/28 Field of Search 72/349, 350, 351, 467

[56] References Cited UNITED STATES PATENTS 5/l97l Shah 72/349 4/1972 Kaminski 72/349 Primary ExaminerRichard .l. Herbst Attorney, Agent, or F irm-johnyy lvielville; ARE litttessetitflley F9$ r [5 7] ABSTRACT A wall ironing tool pack is disclosed, incorporating one or more wall ironing dies and a redraw die to reduce the cup shaped work piece to dimensions for wall ironing, wherein said reduction may amount to about 30 percent, and whereby the risk of fractures, or wrinkling of the work piece is avoided. One or more ironing dies and the redraw die are held in a holder and clamped by means of an annular hydraulic cylinder and piston disposed between any two rings. Hydraulic pressure supplied to said cylinder to actuate said piston is controlled by means of a regulator, whereby adjustment of the pressure on the cup to be redrawn may be made rapidly during operation, to insure the desired redrawn cup for subsequent wall ironing without risking fractures if the pressure is too high, or wrinkles if the pressure is too low, and maintaining the several dies in clamped relation.

.. 7 am 2 Dra g g r WALL IRONING TOOL PACK WITH REDRAW DIE BRIEF SUMMARY OF THE INVENTION In the manufacture of can bodies and the like, the art has largely gone to the two-piece can, wherein the can body and one can end are integral, and a separate end piece is later attached to the open end of the piece comprising the body and one integral end.

The piece comprising the body and an integral end may be produced in several ways. In one of these, a shell cup may be produced from sheet metal by usual drawing techniques, and then the shell cup must be redrawn to a cup of greater length and smaller diameter to prepare it for wall ironing to produce the required body length and wall thickness.

The redrawing procedure requires careful control of the pressure exerted on the shell cup because of the relatively large reduction which must be accomplished. The reduction produced in the redrawing step may be in the neighborhood of 30 percent, e.g. a three and a half inch diameter shell cup may be reduced to two and a half inch diameter for wall ironing. If the pressure is too high, there is a great risk of fracture of the cup, while if the pressure is too low there is an equally great risk of producing wrinkles in the cup. Thus the pressure to which the cup is subjected in the redrawing step must be quite accurately and quickly controlled.

In Kaminski U.S. Pat. No. 3,656,335 there is disclosed a wall ironing tool pack for wall ironing a redrawn shell cup, or a short cup produced by an impact process. A plurality of wall ironing dies are disposed in a pack between fixed ends, with an annular hydraulic pressure ring or an annular cylinder and piston subjected to high pressure disposed between two adjacent wall ironing dies. A relatively light pressure is used to lightly clamp the dies while permitting sliding movement therebetween at their interfaces, for alignment and setup. After a cup has been forced through the tool pack, and the several dies have aligned themselves axially, the clamping pressure is increased to hold the dies in proper alignment with respect to each other and with respect to the punch, throughout its working stroke.

The present invention carries the invention of said patent forward, by incorporating the redraw die into the tool pack, and providing a pressure regulator in the hydraulic circuit to the pressure element in said pack. By these means all the advantages set forth in the above mentioned patent are maintained, and the additional advantage is achieved, of enabling pressure regulation on the redraw die, whereby the pressure to which the shell cup is subjected, may be rapidly and accurately controlled to prevent either fracture or wrinkling.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view with parts cut away to show the tool pack holder and the dies therein.

FIG. 2 is a somewhat diagrammatic cross sectional view showing the arrangement of punches in relation to the dies and the pressure regulator.

DETAILED DESCRIPTION As in the aforementioned Kaminski patent, the tool holder, which is generally indicated at 10, has an internal semi-circular hollow portion 11. A front retainer 12 is in the form of a plate having an opening 13 therein through which the punches move, and is secured to one end of the holder by bolts 14 and the like. A similar holder 12a is secured to the other end of the holder 10.

A hold-down plate 15 also having a part-circular lower face 15a, is secured to the holder by means of bolts 16. It fits between the end plates above described and is provided with an opening 17 to permit access to the pressure element.

In the embodiment illustrated, wall ironing rings are indicated at 18, 19 and 20, and spacers are shown respectively at 18a, 19a and 20a. A stripper is shown at 21. A redraw ring is indicated at 22. The ironing punch is indicated at 23, and the redraw punch at 24.

In the embodiment illustrated, the pressure-element is disposed between the redraw ring 22 and the first wall ironing ring 18. It preferably comprises an annular cylinder 25 and an annular piston 26. Hydraulic fluid is applied through the fitting 17. Suitable O-rings are indicated at 28 for sealing purposes. By reference to FIG. 2, it will be seen that hydraulic fluid is supplied from a pressure source 27 through a pressure regulator 29. The cup to be redrawn is shown at 30.

From the foregoing description it will be clear that the arrangement provides a hydraulic cushion for the redraw die in addition to clamping the ironing rings. This arrangement permits rapid adjustment of the amount of pressure exerted on the cup to be redrawn and ironed, by changing the pressure of the fluid fed into the hydraulic cylinder by means of the pressure regulator 29. By means of quick and precise adjustment during operation, the desired redrawn cup may be achieved without the danger of fractures resulting from too great pressure or wrinkles from insufficient pressure. It may be observed that the effort necessary to redraw tends to compress the fluid in the hydraulic cylinder and this in turn increases the clamping effect on the ironing rings and spacers.

It will be clear that the precise location of the hydraulic cylinder in the tool pack is not of great consequence, although preferably it is disposed between the redraw ring and the first wall ironing ring. Similarly, it will be understood that this invention is not limited to the precise number of ironing rings shown. The device may be made to operate with more or less wall ironing rings by suitable choice of spacers. Therefore, it will be understood that no limitation not expressly set forth in the claims is intended or should be implied.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a tool package comprising a holder having a cavity adapted to receive at least one wall ironing die to cooperate with a wall ironing punch, and an annular, axially expansible member disposed in said tool package, end plates secured to said holder, a hold-down plate arranged to fit between said end plates and be removably secured to said holder to define a compartment for said dies, and means to supply fluid under pressure to the interior of said expansible member, the length of said holder and the axial dimensions of said dies being such that expansion of said expansible member clamps said dies between said end plates; the improvement which comprises a redraw die disposed in said holder in a position ahead of said wall ironing dies, and a pressure regulator in the fluid supply means, whereby the pressure on said redraw die may rapidly and accurately be varied as required, to prevent either rupture or wrinkling of a work piece being redrawn.

4 4. The structure of claim 3, wherein a stripper ring is disposed immediately after the last of said wall ironing dies. 

1. In a tool package comprising a holder having a cavity adapted to receive at least one wall ironing die to cooperate with a wall ironing punch, and an annular, axially expansible member disposed in said tool package, end plates secured to said holder, a holddown plate arranged to fit between said end plates and be removably secured to said holder to define a compartment for said dies, and means to supply fluid under pressure to the interior of said expansible member, the length of said holder and the axial dimensions of said dies being such that expansion of said expansible member clamps said dies between said end plates; the improvement which comprises a redraw die disposed in said holder in a position ahead of said wall ironing dies, and a pressure regulator in the fluid supply means, whereBy the pressure on said redraw die may rapidly and accurately be varied as required, to prevent either rupture or wrinkling of a work piece being redrawn.
 2. A tool package according to claim 1, wherein said expansible member is disposed between said redraw die and the adjacent wall ironing die.
 3. The structure of claim 2, wherein three wall ironing dies are disposed in said tool holder.
 4. The structure of claim 3, wherein a stripper ring is disposed immediately after the last of said wall ironing dies. 